Method of and apparatus for generating the teeth of gears and gear shaper cutters



o. G. SIMMONS HOD OF AND APPARATUS FOR GENER EE'IH OF 1,858,468 ATING THE, A R CUTTERS 4 Sheets-Sheet l May 17, 1932.

'NYENTOR GEARS AND GEAR Filed March 29,

' May 17,1932.

. I o. G. SIMMONS 1,853,468 METHO OF AND APPARATUS FOR GENERATING THE TE OF GE 5 AND GEAR SHAPER CUT F1 March 29, 1930 TERS 4 Sheets-Sheet 2 ATTORNEY5 May 17, 1932.

METHOD OF AND APPARATUS FOR GENERATING THE TEETH OF GEARS AND GEAR SHAPER GUTTERS Filed March 29, 1930 4 Sheets-Sheet 5 INVENTOR .SWM

75m wad/a7 ATTORNEY 5 0. G. SIMMONS METHOD OF AND APPAR May 17, 1932. ATUS FOR GENERATING THE TEETH 0F GEARS AND GEAR SHAPER CUTTEBS 4 Sheets-Sheet 4 Filed March 29, 1930 "NVFNTOgS ATTORNEYS.

Radius f Chmjwulut Base Circle Patented May 17, 1932 PATENT 1 OFFICE OLIVER G. SIMMONS, OF LAKEWOOD, OHIO HE'IHOD OF AND APPARATUS FOR GENERATING T'I-IE TEETH F GEARS AND GEAR SHAPER CUTTERS I Application filed Marches. 1930. Serial No. 440,078.

This invention relates to a method of and apparatus for grinding or generating the teeth of gears or gear shaper cutters to produce thereon the true curvature ofpredeter- 5 mined form. Since it is essential in anapparatus of this character that the interrelation of the movements of the work blank and tool or grinding wheel be correlated, positive and of precise magnitude, the present inven-- tion will be described as practiced with and applied to an apparatus similar to the apparatus shown in my. co-pending application, Serial No. 98,791, filed March 31, 1926, now

Patent No. 1.752.033, issued March 25, 1930,

although it should be fully understood that the invention is in no way limited to such specific application and could be practiced with and applied to other machines for grinding or generating the teeth of gears or gear shaper cutters.

The principal object of the present invention is to provide a method of and apparatus for generating or grinding the teeth of gears or gear shaper cutters, which are more uni- 2 versal in scope than the methods now followed or the machines now used, in that gears or gear shaper cutters of various characteristics may be produced by simple adjustments or changes in the interrelation of the movements of the work blank and the tool or grinding wheel.

A vfurther object is to provide an apparatus of the type set forth capable of producing gears or gear shaper cutters of various characteristics by simple adjustments of certain parts of the machine.

Another object is to provide a method and means by which gears of different pitch diameters may be ground by controlling the measure of magnitude of the relative rectilinear movement between the work blank and the tool or grinding wheel without replacing any of the operative parts.

' A further object is the provision of adjustable means for producing the relative rolling movement between the work blank and the grindingwheel or tool, whereby gears of different pitch diameters may be ground.

A further object is to provide an apparatus which may be operated either on the describing generating principle of action and adjusted to generate gear teeth upon gear blanks of different pitch diameters, or may be op-- erated on the molding generating principle of action and adjusted to generate gear teeth havlng any desired axial pressure angle upon gear blanks of different pitch diameters.

A further object is to provide in an apparaing movement between the work blank and the tool or grinding wheel is effected by means i of a cam arranged on the work spindle and engaging an abutment, means for adjusting the apparatus to grind gears or gear shaper cutters of different itch diameters.

An additional .ob]ect is to provide in an apparatus of the character in which the relative rolling movement between the work blank and the tool or grinding wheel is effected by means of a cam arranged on the work spindle andengaging an abutment, means whereby the samesi'zed camlmay be used to produce gears or 'gear shaper cutters of different pitch diameters.

More specifically a further object of the invention resides 1n the provision of means for altering'the cooperative relation between the cam and its abutment by an adjustment of the abutment, whereby gears of different pitch diameters may be ground without changing the cam.

Additional objects and advantages will appear hereinafter as the description of the invention progresses.

In the accompanying drawings .a mechanical embodiment of the invention is disclosed,

such embodiment being shown as applied to an apparatus similar to that shown inmy copending application, Serial No. 98,791, now Patent No. 1,7 52,033, heretofore mentioned, and in which drawings, Fig. 1, is a fragmentary longitudinal sectional view through the work slide and tail stock when the apparatus is adjusted to operate on the describing generating principle of action, the cam on the work spindle and the abutment with which the cam engages being shown -in side elevation.

Figs. 2 and 3 are views similar to Fig. 1, except that the apparatus has been adjusted 'tus of the character in which the relative rollto operate on the molding generating principle of action, and in Fig. 3 the abutment is shown as adjusted for the machine to operate upon a gear blank of a different pitch diameter than the blank upon which it would operate when adjusted as in Fig. 2, the cam in both Figs. 2 and 3 being the same.

Fig. 4 is a fragmentary side elevational view of the abutment.

Fig. 5 is an end elevational View thereof.

Figs. 6, 7, 8 and 9 are diagrammatic views illustrating the effect of varying the cooperative relationship between the cam and the abutment.

Fig. 10 is a diagrammatic view showing the trigonometric functionsinvolved in the present invention. I

In my copending application, Serial No. 98,791, now Patent No. 1,7 52,033, above referred to, I have disclosed a method of generating upon the teeth of spur gears or gear shaper cutters of a given pitch diameter, involutesurfaces, such method including imparting to a gear blank a rolling movement into and out of cutting engagement with a cuttin element by oscillating the blank while it is eing moved along a rectilinear path in a direction radial to its axls.

In the method therein disclosed it is proposed to generate the involute surfaces upon the teeth by either the describing generating principleof action, or by the molding generating principle of action. In the case of the describing generating principle of action the direction of the rectilinear movement of the blank is normal to the plane of the cutting element or inding wheel, while in the case of the mol ing generating princifple of action the angle between the plane 0 the cutting element and the direction or path of the rectilinear movement of the blank is adjusted to the complemental pressure angle which it is desired to impart to the teeth of the work blank.

In such copending'application I have dis- 1 engages a sationary abutment to effect the rectilmear movement of the slide proportionately to the rate of work spindle.

'In this machine involute surfaces of any desired pressureangle can be generated on the teeth. ofa gear or gear shaper cutter of .a given pitch diameter by means of the angular adjustment of the support upon which angular movement of the J the work spindle slide is mounted with respect to the horizontal, or to the perpendicular to the plane of the cutting element, without replacing any of the elements controlling the rolling movements of the work.

The present invention is an improvement over the method and apparatus just above referred to, in that it enables by means of a mathematical com utation gears or gear shaper cutters of difierent pitch diameters and of different axial pressure angles, to be generated; and more specifically to be generated without changing the cam upon the work spindle, whereas it was necessary in such earlier method andapparatus to employ a 9 different cam for every variation in the pitch diameter of the gear or gear shaper cutter to be ground.

Inasmuch as the present invention necessitates simply changing the construction of 8 the abutment of the apparatus shown in my copending application, it. is not deemed necessary to disclose herein the complete machine, it being considered suflicient to disclose merely those portions of the earlier 9 apparatus wherein the change is made, particularly since it is well understood in the art that the blank and grinding wheel have a the apparatus shown in my copending application, Serial No. 98,791, now Patent No. 1,752,033, should be given, in order to adequately and fully describe the present invention. To that end it should be stated that 1 the apparatus includes a hollow base within which are two electric motors for'operating, respectively, the cutting element and the work spindle with its associated parts. A bed is securely mounted on the base in the 1 usual manner of machine tool construction. An upright swivel base is mounted on the upper portion of the bed, one end of such base containing a pivot journalled in the" upper portion of the bed. The axis of this 1 pivot is also themedian line coinciding with the plane of the face of the cutting element and intersecting the axis of the cutting element s indle. The cutting element may be .in the orm of an abrasive wheel, if the ma- 1 terial to be removed has been hardened, or

in the form of a milling cutter, if the material to he removed is in the soft state, that is, not heat treated to harden same.

I The other end of the upright swivel base is provided with a segment of a worm wheel adapted to meshwith the threads of a worm shaft journalled in bearing boxes fixedly se- I cured to the top of the bed by means of screws. The other end of the worm shaft has secured thereto a minute range drum provided with a helical groove which has a pitch corresponding to the pitch of the threads of the worm shaft. The right hand end portion of the minute range drum is provided with no a knurled extension to facilitate operation of the worm.

A pointer is provided to cooperate wit the drum, which pointer is provided with an arcuate wing in the upper and lower portions to which are secured keys projecting through the wing and engaging the helical groove of the minute range drum. The surface of the drum is suitably graduated longitudinally thereof, the middle of such graduations being zero. Each division or graduation is one minute of a degree'so that if the knurled ex tension is rotated the upright swivel base will be caused to move about its vertical axis to any predetermined angle within a direct readin range of the minute drum. As the drum 1s rotated, the pointer moves, along until the indicating line on the wing coincides with the desired line on the drum, the setting of the swivel base then being effected and maintained by means of suitable bolts extending into the bed. The upper surface of the worm wheel segment is graduated in quarter degrees to a maximum of 5 on each side of zero, while the top of one of the hearing boxes is provided with a .zero line coinciding with the zero line of the surface of the segment when the indicating line of the wing coincides with zero on the minute range drum.

The graduations on the segment surface are to enable the operator to quickly determine by inspection approximately the angular setting of the upright swivel base and more accurately to the exact minute by means of visual inspection of the minute drum. It .is important that the cutting face of the cutting element be set at the correct angle with respect to the axis of the work whether the work be a gear or a gear shaped cutter. The top of the upright swivel base is provided wlth V-ways to which an upright is slidably connected, which upright is adapted tobe moved on the V ways longitudinally thereof toward or away from the pivot axis of the base by means of a screw having threaded engage- '-ment with a nut secured to the base. The outer end of this screw has secured thereto a graduated hand wheel, while interposed between the hand wheel and a shoulder of the screw is an extension bearing fixedly. secured to the lower portion of the upright. By rotilting the hand wheel the u right is moved toward or away from the pivot axis of the swivel base; The face of the upright is pro- .Wided with V-ways'adapted to receive the V- ways of a slide which carriesthe cutting elemerit. A bracket is secured to the upper por tion of the upright and carries a shaft, one

end of which is provided with a hand wheel and the other end of which is provided with a spiral gear fixedly secured thereto. This gear is located inside of a casing and is adapted to engage the teeth-of a mating spiral gear inside another casing, this last-mentioned is adjustable alon the't gear being fixedly secured to the upper portion of a screw, the threads of which engage a nut carried in'the upper. portion of a tube, the lower portion of said tube being fixedly secured to a boss on the upper portion of the slide which carries the cutting element.

By rotating the .hand wheel in one direction, the slide may be moved upwards and ,if rotated in the opposite direction the slide will be moved downwards. -'On each side of the slide are bearing boxes in which is journalled the cutting element shaft, such shaft being connected with a driving motor in the base by means of a self-adjusting belt and pulley drive. A suitable sharpening or dressing means is provided for maintaining a smooth grinding surface and for keeping the tooth engagin portion of the cutting element in a single p ane.

The work supporting mechanism and the actuating mechanism for the work spindle and work spindle slid-e are mounted at one side of the bed. The'work supporting mechport, indicated at 10 in the present drawings, mounted for angular adjustment upon a horizontally disposed bearing secured to the machine below the top of the bed, suitable means being provided for angularly adjusting'the swivelled support. The swivelled work sup port extends along one side of the bed of t e machine, and has a slide indicated in the present drawings at 11, mounted thereon in suitable ways, which supports a horizontally disposed work spindle 12 adapted to have the .anism comprises a swivelled work slide supwork blank secured thereto adjacent one of its ends. The work spindle 12 is mounted within the intermediate sleeve 13, which, in turn, is mounted within an outer sleeve 14 suitably journalled in supports arranged on the slide.

The cam-15 of spiral curvature, and prefutment is carried y a tail stock, and H gent to said base circle to provide" or tooth depth and flank fullness-(1n the c se of gear shaper cutters), being mounted on the forward end of the abutment spindle 17 having a sliding fit in the tail stock 18, fixed with respect tothe swivelled work slidesupport 10. Theabutment spindle 17 is adjustable longitudinally of the swivelled support 10, by means of a tail stock screw (not shown) which is operated.

by means pf a hand wheel, while suitable clamping-screws are provided forclamping the abutment s indle in various adjusted.

positions. The ase of the tail stock is fixing in a suitable counter-weight housing.

edly secured to the right 'hand end portion of the support by means ofcap screws. The cam 15 serves to impart a linear movement to the slide 11 when the work spindle 12 is oscillated, such linear movement being proportional to the rate of angular movement of the spindle, and so designed as to impart the correct generating rol ing movement to the work spindle during the grinding operation; the rotary and linear movements of the spindle being the movements which would be im arted to it by the gear being generated in rol in on its imaginary rack, the lane of the grin ing Wheel coinciding with t 3 lane of a face of a tooth of the rack, as is we 1 understood in the art. 1

In order that the operation of the machine may be continuous, means is provided for i11 dexing the work blank during the intervals between successive en ageinents of the rolling work blank with t e grinding wheel. It should suflice here to say that a suitable indexing head (not shown), is mounted adjacent one end of the work spindle for intermittently rotating the intermediate sleeve 13 and the spindle 12 through an angle corresponding to one tooth space every time the gear blank is moved out of engagement with the grinding wheel.

The work spindle 12 is normally connected to rotate with the intermediate sleeve 13, being connected with such sleeve by means normally locking the same to the sleeve, but permitting' adjustment of the s indle within the sleeve to obtain proper a justment of the gear blank.

The indexing mechanism, above referred to, serves to .lock the sleeve 13 to the outer sleeve 14, so" that thework spindle rotates with the cam 15 during the grinding operation, and operates to rotate the sleeve 13 within the sleeve 14 to index the blank during that portion of the movement of the work spindle slide'll in which the work blank is out of engagement with the grinding wheel, and to lock the sleeve13 to the outer sleeve 14 during the intervals between indexing actuations of the sleeve 13.

In the operation of the machine the outer sleeve 14 and the cam 15 are oscillated through an angle sufiicient to impart the desired amount of linear movement to the slide 11 by means of a connecting rod secured at its upper end to the sleeve 14 and adjustably.

connected at its lower end to a crank arm which is oscillated through suitable driving connections by one of the motors in the hollow base of the machine.

The work spindle slide 11 is yieldingly pressed in a direction to hold the cam 15 in engagement with the abutment 16, by means of a counter-weight cable which is attached to the forward end of the slide 11 and extends over guide sheaves to a counter-weight hang- During rotative movement of the cam 15 in one direction the slide 11 is moved forwardly by the cam, through the action of the same against the abutment, and during the rotative movement of the cam in the opposite direction the slide is moved rearwardly by the counter-weight, such movement being controlled by t e engagement of the cam with the abutment.

In the operation of the machine shown in my copendlng application, Serial No. 98,791,

, now Patent No. 1,752,033, the gear shaped blank is first accurately positioned with respect to the grinding wheel by suitable adjustments of the 'work spindle and of the cam and abutment, after which the driving motors are started, causing the slide to be reciprocated on the swivelled support to carry the gear shaped blank into and out of engagement with the grinding wheel, as is well understood in the art. The curvature of the cam is such that the combined rotary and linear movement of the blank relative to the face of the cutting element or grinding wheel, causes the cutting element to generate on the face of the tooth of the blank in engagement therewith, the proper curve for said tooth.

When the swivelled-work support is in the horizontal position, the path of movement of the work spindle slide is perpendicular to the face of the grinding wheel, the machine then being operated on the describing generating principle of action, while with any angular position of the swivelled work support the machine will be operating on the molding generating principle of action and the pressure angle resulting from the curve generated on the tooth faces will be exactly equal to the angle of the swivelled slide support with respect to the horizontal. In thls last instance, the swivelled work slide support may be accurately set at an angle to the horizontal, corresponding to the pressure angle of the teeth of the gear or gear shaped article to be generated, and the curve on the face of the cam if an involute curve must have an evolute equal in diameter to the diameter of the selected pitch circle of the gear shaped article to be ground. The abutment is arranged so that the point of contact between the cam and the abutment lies in the plane of the tangent to the evolute circle of the cam which is parallel to the plane of movement of the axis of the work spindle; that is, it is at an angle to the horizontal corresponding to the pressure angle, the lead of the cam for one turn of the spindle measured on this tangent line being equal to the perimeter of the pitch circle of the gear to be ground.

When the cam is changed the point of contact between the cam and abutment lies in the plane coinciding with the tan ent to the evolute circle of the new cam whic is parallel to the plane of movement of the axis of the work spindle.

If the curve of the cam is generated from an evolute or base circle of, for example, three inches diameteror on any other spiral curve having a lead along a straight line corresponding to the lead of the involute of a three inch base circle, any one of an infinite number of involute curves may be generated on the face of the teeth of a corresponding three inch pitch diameter work blank, by the simple expedient of setting the swivel support to the proper pressure angle. This for the reason that if the involute curve has been generated from an evolute of three inches diameter, there will be a resultant movement of the slide corresponding to the measure of the perimeter of the evolute which is in this instance three inches in diameter. It is to be observed that this movement of the slide corresponds to and is identical with the movement of a rack engaging a pinion of three inches pitch diameter. It is obvious that the diametral pitch and pressure angles can be infinite in number. It is necessary when the machine is set to operate on the molding generating principle of action that a di erent cam be provided for each pitch diameter.

For example, if, as heretofore referred to, the work is of three inches pitch diameter, which is one size of a well known gear shaper cutter, one cam only will be necessary for any pitch or pressure angle for a three inch gear shaper cutter or gear, as the case may be, and

. the one cam, as described, arranged for three inch pitch diameter cutters, will be suitable for a three inch pitch diameter cutter of any pitch or pressure angle. This holds true with respect to four inch gear shaper cutters 1n which case the curve of the'cam would be generated from an evolute of four inches diameter, and this cam, like the previously mentioned cam, will serve for any four 1nc gear shaper cutter'or gear, as the case may be, for any pressure angle and pitch within the capacity of the machine.

The point of contact between the cam and abutment will lie in the plane of different tangent lines when the different cams are used; as for example, in the case of the three -inch cutter, the tangent line must' be one and one-half inches removed from the axis of the work spindle, and in the case of the four inch cutter, it must be removed two inches from the axis.

When the machine is operating on the describing generating principle of action, it is necessary that the curve of the cam be identical'with the curve desired to be produced on the teeth of the work. For example, let it be assumed that it is desired to generate involute curved surfaces, formingthe faces of the teeth of a gear shaper cutter or gear of say three inches pitch diameter, 20 pressure angle. The curve of the cam, therefore,

is the involute curve identical with the curve to be generated from a base circle determined by a pressure angle of 20 to a three inch or the describing generating, because the lead of the cam, for a given gear for one turn of the spindle, must be equal'to the measure of the perimeter of the selected pitch circle in the molding generating principle of action and equal to the measure of the perimeterof the evolute in the describing generating principle of action.

In order to more fully illustrate this fact, it will be assumed that the apparatus is flmc tioning on the molding generating principle and that the gear shaped blank to be ground is of three inches pitch diameter. Therefore, the involute curved surface of the cam will have an evolute or base circle of three inches diameter, since its involute curve will have a lead along a line tangent to its base circle or evolute, equal to the circumference of such base circle or evolute. Of course any desired pressure angle may be imparted to the teeth of the blank by angularly adjusting the path of the rectilinear movement of the blank with respect to the plane perpendicular to the plane of the cutting element. However, if it is desired to operate on gear shaped blanks of a any other pitch diameter, it is necessaryto employ a cam having an evolute or base circle of the selected diameter.

The present invention contemplates, in its broader aspect, the provision of a method and apparatus for generating involute tooth surfaces or gear shaped blanks, whereby the relative rolling movement, between the blank v and the cutting element, may be changed for a gear shaped blank of a different pitch diameter in accordance with a mathematical computation later to be referred to.

One way in which it is proposed to accomplish this is by changing the cooperative relationship between the cam and its abutment,.

to the end that the same cam can be employed to impart, within certain limits, different measures of linear movement to the blank, based on a formula derived by'mathematical computation.

In other words, the effective lead of the cam corresponds to the actual lead whenv the cam surface engages the abutment at-zero pressure angle. Whereas, when the cam surface engages an abutment set at an angle other than 90 to the plane of linear movesponds to a cam having an involute curve of a larger diameter evolute.

Thus the present invention adapts a cam of a given lead to be used to grind gears and gear shaped cutters of different pitch diameters.

When an involute cam engages its abutment in the plane of the tangent to its evolute, which is parallel with the plane of the rectilinear movement of the cam and blank carrying spindle, the pressure angle between the cam and abutment is zero and the rectilinear movement of the cam, in the direction of the arrow W, for one turn of the cam, from the position shown in Fig. 6 to the position shown 2 in Fig. 7, equals the measure of the perimeter of the evolute of the cam. This situation is diagrammatically shown in Figs. 6 and 7, the curve V representing the involute surface of the cam; T, the tangent; B, the base or ,evolute circle; and A, the measure of the lead of the cam for one turn of the spindle. It is thus apparent that A (lead of the cam) =diameter B-pi and since, as we have seen, the lead of the involute cam must equal the measure of the perimeter of the pitch-circle of the gearto be ground:

A (lead of cam) dia. PC (gear to be ground) p'ifor zero pressure angle dia.'B-p'i=dia. PO-pi 4c in which PC and B are equal.

Since the pressure angle between the cam and abutment is normally zero, and it is desired to establish a given pressure angle to accommodate a larger pitch circle we have:

' cos PA= 1 hence am. B- it; LT dia. PU-pi dia. B-pidl8. PU-pi size of cam cos P. D. of gear to be ground The example of the practical application of this formula given below is diagrammatically shown in Figs. 8 and 9.. Assuming that the cam being used is a four inch cam (evolute offour inches diameter) and the gearto be ground has a four and one-half inch pitch diameter, then the relationship between the cam and abutment must be changed fromnormalfso that the four inch cam will impart, for one turn of the work blank spindle,

a rectilinear movement to the slide, when the blank isin rolling engagement with the cutting element, equal to the" measure of the erlmeter of the pitch circle of the gear to e. ground, such relationship beingobtained with a rearwardly 4 cam on work spindle 4.5 PD of gear to be ground :v=PA to be established between cam and abutment hence 4 cos a: .888888 m=27 16 PA between cam and abut- I ment.

The relationship between the cam and abutment being adjusted so that a pressure angle of 27 16' is established between them,

the four inch cam will have an effective lead equal to the measure of the perimeter of the pitch circle of a gear of four and one half inches P. D., or equal to the measure of the lead of a cam having an evolute diameterof four and one-half inches.

In Figs. 4 and 5, a mechanical embodiment of an abutment structure for obtaining the different relationships, between the cam and abutment is illustrated.

As previously stated the abutment, indicated generally at 16, is mounted on the forward end of the abutment spindle 17 having a sliding fit in the tail stock 18 carried by the tail stock base which is fixedly mounted on the swivel work support 10, whereby the positions of the tail stock and of. the abutmovement of the slide, irrespective of the angular position of the swivel work support.

In my earlier application, referred to, the cam engagedthe abutment on the tangent line to the evolute parallel with the plane of the swivel work support 10.

In the present application the cam and abutment will correspondingly contact when the pressure angle between them is zero, but when the pressure angle is other thanfzero, the point of contact will be on a line tangent to t e evolute or base circle and will intersect the first mentioned tangent line, the included angle being the pressure angle between the cam and abutment."

The structural embodi ent illustrated of an abutment suitable for this purpose comprises a member having a plain back portion 19 forwardly cut a way, adjacent its lower end at 20 and provided just above the cut-out projecting centrally. arranged stub shaft 21'. This member is 081- tioned upon the end of the abutment splndle 17, such end of the spindle being formed complementally to the portion 19 and cutout 20, the stub shaft 21 extending into a bushing arranged in a recess 22 formed in the spindle, being held therein by the set portion 19 between the points 26 and ,27 (see Fi 5), such portion 19 extending forwardly tween the arms to the position indicated by the line 28 in Fig. 4.. The pivoted arm 29 is arranged between the arms 24 and 25, being pivoted at its lower end on a pivot bolt 30 extending through the arms. The rear side of the pivoted arm 29 is shaped as indicated by-the dotted line 31 in Fig. 4.

The upper end of the pivoted arm 29 is i provided with a rearwardly extending arenis operating ate portion 32 having a concentric a'rcuate slot 33 therein. The bolt 34 extends through the arms 24 and 25 and through the arcuate slot 33, whereby the pivoted arm 29 may be swung to various positions and held therein when the nut 35 on one end of the bolt 34 is tightened, the arms 24 and 25 having sufiicient flexibility to permit them to be drawn.

in against the arcuate portion 33 of the pivoted arm 29 to clamp said arm in position to form a unitary part.

The upper end of the pivoted arm 29 at the forward end of the arcuate portion extends above the upper end of the arms 24 and 25, with the upper edge of the arcuate portion curving rearwardly therefrom. The upper end or edge of the pivoted arm 29 and the arcuate portion 32 have a downwardly inclined bevelled part 36 provided with graduations 37 which cooperate with graduations 38 on the downwardly inclined bevelled upper end 39 of the arm 25, thus forming a scale and vernier for giving the readings of the position of the pivoted arm 29. \Vhen the reading is zero degrees the pivoted arm 29 is set normal and in the describing generating position shown in Figs. 4 and 5, the plain flat forward edge 16' of the pivoted arm 29 lying forwardly of the corresponding edges of the arms 24 and 25 and perpendicular to the direction of movement of the adjustable abutment spindle 17, said edge of the pivoted arm 29 constituting the abutment surface proper 16. This position of the pivoted arm 29 is used when the pressure angle between the cam and abutment is zero de-' but Whenever a different pressure angle is to he established the pivoted arm 29 is swung to the proper position determined by the formula above set forth. See Figs. 3, 8 and 9. g

It is believed that the operation of the apparatus and the manner in which the method may be practiced are apparent from the foregoing description. As long as the machine on gears of a pitch diameter equalto the diameter of the evolute of the cam on the work spindle, the pivoted arm 29 is set so that the graduations 37 and 38 indicate Zero pressure angle between the cam and the abutment. The swivel work support .10., is positioned horizontally, as shown in the pivoted arm 29 the type set forth in between the cam and abutment by swivelling swivel work support 10, as shown in Figs. 2 and 3. Whenever it is necessary to operate on a blank of a different pitch diameter is adjusted to the proper position to enable the cam to impart the proper rolling movement to the blank with respect to the grinding wheel, it of course being understood that the new pitch diameter is preferably greater than the diameter of the cam evolute. This is shown in Figs. 8 and 9. p

Although the invention has been specifically explained in connection with a machine of my copending appllcation, it should be understood that the description is merely illustrative and that other Ways of varying the effective relative rolling movement, between the blank and cutting element for the purpose desired, are equally within the purview of the invention, as isalso the use of different machines for carrying it out.

It has heretofore been proposed that a slight angular adjustment of the abutment be provided to enable same to be positioned with precision to a given cam involute to compensate for slight mechanical errors of workmanship in the cooperating machine elements, but in the present method and apparatus the same cam is utilizable in generating the teeth of gears and gear shap'er cutters of any pitch diameter. within the limits of the machine.

Having thus I claim is:

1. The method of generating involutc surfaces on the teeth of gear shaped articles of different pitch diameters by means of a cutting element engaging 7 blank in a single plane while the blank is oscillated about its axis and is simultaneously toward and away from the cutting element by means of an involute cam engaging an abutment, which comprises varying in predetermined amount the relationship between the cam and abutment to change the correlated linear movement of the blank to generate the teeth of gear shaped articles of different diameters while using the same cam.

2. The'method of generating involute surfaces on the vteeth of gear shaped articles of different pitch diameters and of any described my invention, what the teeth of the given a correlated linear movement ment of the blank to generate the teeth of gear shaped articles of difleren't pitch diameters while using the same cam, and adjusting the direction of such linear movement of the blank to an angle with respect to a plane perpendicular to the plane of the cutting element equal to the desired axial pressure angle.

3. The method of generating involute surfaces on the teeth of gear shaped articles of difierent pitch diameters by means of a cutting element engaging the teeth of the blank in a single plane while the blank is oscillated about its axis and is simultaneously given correlated linear movement toward and away from the cutting element by means of an 1nvolute cam engaging an abutment normally along the tangent to the evolute of the cam parallel with the plane of the linear movement of the blank, which comprises varying the relationship between the cam and abutment so that the engagement therebetween is along a tangent to the evolute at an angle to the plane of thelinear movement of the blank to thus change the measure of such linear movement and to generate the teeth of gear shaned articles of different pitch diameters.

4. The-method of generating involute surfaces on the teeth of gear shaped articles of difi'erent pitch diameters and of any desired axial pressure angle by means of a cutting element engaging the teeth of the blank in a single plane while the blank is oscillated about its axis and is simultaneously given correlated linear, movement toward and away from the cutting element by means of an involute cam normally engaging an abutment along the tangent to the evolute of the cam parallel with the plane of the linear movement of the blank, which comprises varying the relationship between the cam and abutment so that the engagement therebetween is along av tangent to the evolute at an angle to the ,plane of the linear move-' ment of the blank, and adjusting the direction of such linear movement of the blank to an angle with respect to a plane perpendicular to the plane of the cutting element equal to the desired axial pressure angle.

.5. The method of generating involute surfaces on the teeth of gear shaped articles of different pitch diameters by means of a cutting element engaging the teeth of the blank in a single plane while the blank is oscillated about its axis and is simultaneously given correlated linear movement toward and away from the cutting element by means of an involute cam engaging an abutment normally along the tangent to the evolute of the cam parallel with the plane of the linear movement of the blank, which comprises varying the relationship. between the cam and abutment so that the engagement therebetween is along a tangent to the evolute intersecting the first 'mentioned tangent such that the cosine of the included angle equals the diameter of the evolute divided by the pitch diameter of the gear to be ground.

6. The method of generating involute surfaces on the teeth of gear shaped articles of difierent pitch diameters and of anydesired axial pressure angle by means of a cutting element engaging the teeth of the blank in a single plane while the blank is oscillated about its axis and is simultaneously given correlated linear movement toward and away-from the cutting element by means of an involute cam engaging an abutment normally along the tangent to the evolute of the cam parallel with the plane of the linear movement of the blank,

which comprises adjusting the relationship between the cam and abutment so that the engagement therebetween is along a tangent to the evolute which intersects said first mentioned tangent with an included angle whose cosine is equal to the diameter of the evolute divided by the pitch diameter of the gear to be ground, and adjusting the direction of the linear movement of the blank to an angle with respect to a plane perpendicular to the plane of the cutting element equal to the desired axial pressure angle.

7.- In a machine of the character described and of the type having a cutting element and an oscillatable work carrying spindle adapted to have a blank secured thereto, a cam fixedly arranged with respect to said spindle, an abutment with which said cam engages to cause a linear movement of said spindle in a radial direction with respect to its axis toward and from the cutting face of the cutting element, and means for adjusting said abutment to change the relationship between said cam and abutment whereby gears of different pitch diameters may be generated on the machine without changing the cam.

8. A machine of the character-described and of the type having a rotary cutting element provided with a cutting face in a fixed plane comprising a slide, a. support for said slide and angularly adjustable about a horizontal pivot, a spindle carried by said slide and adapted to be oscillated and to have a gear shaped blank secured thereon, a cam fixed with respect to said spindle, an abutwhereby the relationship between the cam and of the pitch circle of the gear shaped article abutment may be varie p to be ound. v

9. The method of generating involute sur- 13. e method of generating involute faces on the teeth of gear shaped articles ofdifferent pitch diameters, by means of a cutting element engaging the teeth of the blank in a singleplane while the blank is oscillated about its axis and is simultaneously given a corelated linear movement toward and away from the cutting element by means of an involute cam normally engaging an abutment with a zero pressure angle therebetween, which comprises introducing predetermined pressure angles between the cam and abutment, such that the corelated linear movement of the blank will be changed to generate the teeth'of gear shaped articles of different pitch diameters.

10. The method of generating involute surfaces on the teeth of gear shaped articles of difi'erent pitch diameters by.means of a cutting element engaging the teeth of a blank in a single plane while the blank is oscillated about its axis, and is simultaneously given a corelated linear movement toward and away from the cutting element by means of an involute cam normally engaging an abutment with a zero pressure angle therebetween, which comprises introducing a pressure a-nglebetween the cam and the face of the abutment such that the efi'ectivevlead of the cam corresponds to a cam havin an involute curve of a larger diameter evo ute.

11. The method of generating involute surfaces on the teeth of gear shaped articles of different pitch diameters by means of a cutting element engaging the teeth of the blank in a single plane while the blank is oscillated about its axis and is simultaneously given a corelated linear movement toward and away from the cutting element by means of an involute cam normally engaging an abutment with a zero pressure angle there- ,between, which comprises introducing a pressure angle betweenthe cam and the face of the abutment, such that the efiective lead of the cam corresponds to the lead of a cam having an involute curve of an evolute whose diameter is equalto the diameter of the pitch circle of the gear shaped article to be ground.

12. The method of generating involute surfaces on the teeth of gear shaped articles of different pitch diameters by means of a cutting element engaging the teeth ofthe blank in a single plane while the blank is oscillated about its axis and is simultaneous- 1y 'ven a corelated linear movementtoward an away from the cutting element bymeans of an involute cam normally engagin .an

abutment with a zero pressure angle t erebetween, which comprises introducing a pressure angle between the-cam and the face of the abutment such that the effective lead of the dam equals the measure of the perimeter surfaces on the teeth of gear shaped articles from the cutting element by means of an involute cam normally engaging an abutment with a zero pressure angle therebetween, which comprises introducing predetermined pressure angles between the cam and abutment such that the corelated linear movement of the blank will be changed to generate the teeth of gear shaped articles of different pitch diameters, and adjusting the direction of such linear movement of the blank to various angles with res ect to a plane perpendicular to the plane 0 the cutting element equal to the desired axial pressure angles.

14. The method of generating involute surfaces on the teeth of gear shaped articles of different pitch diameteirs and of any desired axial pressure angle by means of a cutting element engaging the teeth of a blank in a single plane while the blank is oscillated about its axis and is simultaneously given corelated linear movement toward and away from the cutting element by means of an, irivolute cam normally engaging an abutment with a' zero pressure angle .therebetween, which comprises introducin pressure angles between the cam and the ace of the abutment such that the effective leads'of the cam correspond to cams having involute curves of. larger diameter evolutes, and adjusting the direction of such linear movement of the blank to various angles with respect to a plane perpendicular to the plane of the'cutting clement equal to the desired axial pressure an les. p

15. T e method of generating involute surfaces on the teeth of gear shaped articles of difi'erent pitch diameters and of any desired axial pressure angles by means; of a cutting element'engaging the teeth of a'blank in a single plane while t blank is oscillated aboutits axis and is simultaneously given corelated linear ovement toward and away from the cutting lement by means of'an involute camnormally engaging an abutment with zero pressure angle therebetween, whichcomprises introducing pressure angles between the cam and the face of the abutto the pitch diameter of the gear shaped articles to be ground, and adjusting the direction of such linear movement of a blank to variousangles with respect to a plane perpendicular to the plane of the cutting element equal to the desired axial pressure angles.

16. The method of generating involute 5 surfaces of the teeth of gear shaped articles of diiferent pitch diameters and of any desired axial pressure angle by means of a cutting element engaging the teeth of a blank in a single plane while the blank is oscillated about its axis and is simultaneously given corelated linear movement toward andaway from the cutting element by'means of an involute cam normally engaging an abutment with a zero pressure angle therebetween, which comprises introducing pressure angles between the cam and the-face of the abutment such that the effective leads of the cam are equal to the measures of the perimeters of the pitchcircles of the gear 2 shaped articles to be ground, and adjusting the direction of such linear movement ofthe blank to various angles with respect to a plane perpendicular to the plane of the cutting element equal to the desired axial pres- 2 sure angles.

17. A machine of the character described and of the type having a rotary cutting element rovided with a cutting face in a fixed p ane and comprising a slide, a support 80 for said slide, a spindle carried b said slide and adapted to be oscillated an to have a gear shaped blank secured thereon, a cam fixed with respect to said'spindle, and an abutment with which said cam engages to 85 effect a' rectilinear movement of the slide with respect to the cutting element, said element including a pivoted member havin a cam engaging face whereby said mem er may be FOSltlOIlGd at various angles to the 40 plane 0 linear movement of the slide to vary the relationship between the cam and the abutment, and means for maintaining .said member in the different angular positions. I

18. A- machine of the character described and of the having a rotar cutting element provi ed with a cutting ace in a fixed plane and com rising a slide, a sup ort for said slide, a spindle carried by said s de and 80 adapted to be oscillated and to have a ear sha d blank secured thereon, a cam ed wit re ct to said spindle, and an abutment with whlch said 'cam engages to effect a rectilinear movement of the slide with respect it to the cutting element,-said abutment comand an oscillatable wor and comprising a slide, a support for said slide, a spindle carried by said slide and adapted to be oscillated and to have a gear shaped blanksecured thereon, a cam fixed with respect to said spindle, an abutment with which said cam engages to effect the rectilinear movement of the slide with respectto the cutting element, said abutment comprising a pair of parallel spaced arms, a third arm pivotally arranged between said armsand having its forward face forming .a cam engagin surface of the abutment, means whereby sai third named arm may be arranged in various positions of adjustment to change the pressure angle between the cam and the abutment, and means on the abutment to indicate the pressure angle at which the third arm is adjusted.

20. An abutment adapted to be used in a machine of the type having a rotatable cutting element provided with a cutting face operating in a fixed plane, an oscillatable work carrying spindle adapted to have a blank secured thereto and a cam fixedly arranged thereon for cooperation with an abutment to cause a linear movement of the spindle in a radial direction with respect to its axis toward and from the cutting face of the cutting element and comprising a cam engaging portion adjustable to various angular positions with respect to the lane of linear movement of the work spin e to vary the pressure angle between the cam and the abutment, and means on the abutment indicating the existing pressure angle between the cam and the abutment at the various positions of adjustment.

'21. In a machine of the character described and of the type havin a cutting element spindle relativel movable linearly toward and from eac other, means for producing said relative movement comprisin an oscillatable cam and an abutment with w ich said cam engages, and means for adjusting said abutment to change the pressure angle between said cam and abutment to vary the measure of said relative linear movement. a

In testimony whereof, I hereunto aflix my signature.

' OLIVER G. SIMMONS.

prising a-pa1r of spaced-parallel arms, a

. third arm pivoted therebetween with its front face adapted to form the cam engaging surface of the abutment, and means for 0 maintaining said third arm in various positions of adjustment to change the relationship between the cam and the abutment.

19. A machine of the character described of the type having a rotary cutting element provided with a cutting face in a fixed plane 

